Device for calculating time



July 10, 1928. 1,676,912

- F. C. MEACHAM DEVICE FOR CALCULATING TIME Filed Nov. 15, 1925 fizz/0M4Madam avwewtoz 32x 1; Qua/nude Patented July 10, 1928.

EEEEEEIoK c. MEACHAM, 0E GARDEN GITYyNEW YORK.

DEVICE FOR CALCULATING TIME.

' Application filed. November 13, 1925.- Serial no, 68,815.

My invention relates to a device foruse in,

the calculation of time by means ofthe position of certain stars; thisis accomplished by reading, on my device, the'relative position of thestars, followed by certain calculations, as will be hereinafter fullyset forth. The object of my invention is to enablethe quick andeasydetermination of such relative position with a reasonable degree ofac-'curacy under the conditions in which the device 1s ordinarily used;another object of.

my invention is to provide a device forsuch purpose which shall becompact and reasonably simple and. cheap to manufacture in g tended)meets device. I, v

In the drawing, 21 represents-a disk which may be of transparentmaterial, such as celluloid'. The. disk is preferably divided into fourequal sectors by the perpendicular diameters 25., 26. The periphery ofthe disk is also divided into twelve equal spaces by the diameters andthe lines indicated at 22 or by other suitable means for indicating thedivisions of the disk; these spaces are again preferably divided, as bythe lines 23, 24, in-

to four equal parts. The lines 22, as well as the outer extremities ofthe two diameters, may be numbered, as indicated at 27, in the samemanner as the dial of a clock, from 1 to 12 inclusive. At the outer endof one diameter, adjacent the numeral 12, I prefer to place anoutwardly-pointing arrow-head, or other easily noticeable mark 28, toindicate clearly the uppermost point of the disk. 7

V In my preferred form, a central aperture is stamped out of thematerial'of the disk and a small metal eyelet 29 inserted therein.Carried by the eyelet 29 is an arm 3O which may be transparent. The arm,when extended, projects beyond the outer edge of the disk. The eyelet isriveted over a portion of the arm to hold it in rotatable. relation tothe disk. The eyelet 29 is preferably a true eye'- let-i. e., of suchcharacter that it will not obstruct clear vision through the aperture atthe center of the disk.The'arm 30.has preferably a length about equal tothe diam eter of the disk and it may be slotted 1 throughoutapproximately halfof its length, as indicated at 31, so that, whenthe'deviceis notin use, the arm may slide along theeyelet over thefaceof the disk into position where it does not project beyond the edgeof the disk. It will be understood that this 7 is merely for compactnessand convenience in carrying. The longitudinal center ofthe armisdelined, as by the line 32, which preferably extends from the outerendof the arm to apomtwhich (when the arm is fully X- or crosses: the edgeof the disk. It will of course be understood that any other suitablemeans may be used to define, by means of the arm, airadial line; forexample, the outer end of the arm may be offset so that one edge thereoflies along' a radius (extended) of thedis'k.

I will nowdescribe one method of using my dev ce; this method enables asurprisingly accurate calculation. of time, at least when'used at ornear aline of longitude which determines the standard time: for thatwhen my device isu-sed locality. Of course,

atlsome distance eastlor west of such line of longitude, the calculatedtime will not agree so well with the standard time, but it willeverywhere agree very closely with the true time or sun-time.

.In the method here described, my device is used to determine therelative position of the North Star or Polaris and the two stars intheconstellation Ursa Major known as on and ,8 or the Pointers. Mydevice is held before the eyes of the observer-say eight inchesfrom theeyes, with the arrowhead 28 pointing upward and the diameter in avertical plane through the me- 25 lying The presence of the twodiameters ridian.

on the face of the disk'assists the observer inproperly positioning it.The diskshould.

beheld so as to lie in a plane perpendicular to the line of visionbetween the observer and Polaris. The arm 30 having been fully extended,the that Polaris is visible through the hole at the center of thedisk-.as indicated at 33in the drawing. The arm 30 is then rotated,

without disturbing the position of the disk,

until the Pointers of the constellation Ursa Major, the line 32 or theindicated at 34, 35, lie'along line 32 if continued. Thisadjustmenthaving been made, the relative device is then so positionedposition of the stars is read by taking vthe.

reading on the disk as determined byjthe add to that the number ofmonths and quarter-months that have' elapsed during the calendar year inthis case 7 (January to 'J uly, inclusive, being 7 and the eight days ofAugust being approximately one quar ter); the sum then equals 8%; next,double I this-sumgivin in this case, 17 subtract this final amount from-4O g1ving 22%; This last figure gives the time.

Wher e,as here, the time given is greater than 12, then 12 or 2st or 36,may be de; ducted so that the net result will be less tha-n 12.Proceeding thus in the example given, '12 is deducted from 223/ leaving10% which means that thetim'e is 10 :45. I am. aware that modificationsmay be v made in my device by those skilled in the art and, therefore, Idesire protection for all such forms of my device as come within thescope of the appended claims. 3

I claim:

1. A stellar time indicator comprising a disk having a central openingand a marginal scale, a longitudinally slotted arm adapted to bepositioned to lie'wholly within 1 the margin of said disk, meansassociated withrsaid' central opening having an open- 'ing in alignmenttherewith, said slotted arm being rotatably and slidably' carried bysaid means and having aline'thereon which, i!-

pro ected, would intersect the center of said disk. r i. r

2. Astellar time indicator comprising a disk having a central openingand a marginal scale, a longitudinally slotted arm of transparentmaterial"adapted-to be positioned to lie wholly. within the margin ofsaid disk, means associated with said central opening having an openingin alignment therewith, said slotted arm being rotatably andslidablycarried by said means and having a line thereon which, if'projected,would intersect the center 'of'said disk,'said disk having a diametralline thereon adapted. to be pointed toward the zenith-when 'anobs'ervation is to bemade. l

3. A'stellar time indicator comprising a disk having a' central openingand a martransparent 'material, an through said central opening andthrough rotatably and slida-bly carried by said eyelet and having a linethereon,'which, if pro jected, would intersect the center of said' disk,said arm having substantially the length of the diameter of said diskandthe slot therein being substantially equal in length to the radius ofsaid disk-whereby ginal scale, a longitudinally slotted arm of 3 eyeletpassed 7 said arm may be positioned to lie wholly withincthe margin ofsaid diskfsaid disk having a diametral line thereon adapted 'tobepointed toward the zenith when an observation is to be made.

FREDERICK C. MEAOHAM.

6o the slot in said arm, said slotted arm being 1

